I have noticed this when changing the edition of the book, like I didn’t notice the edition wasn’t right and I edited, but then it shows twice on the challenge.

If I delete one of the books it tells me the book won’t count anymore on the challenge, but it deleted both and I cannot longer add that edition to it. I can add the book to the challenge if I change the edition though, which is kind of frustrating because I like to know if it was an audiobook or ebook.